High-strength cold-rolled steel sheet with yield strength level of 700MPa and manufacturing method thereof

Abstract

The invention provides a high-strength cold-rolled steel sheet with the yield strength level of 700MPa and a manufacturing method thereof. The method comprises a thin stab casting and rolling flow, a cold rolling flow, an annealing flow, a finishing flow and the like. Refined molten steel comprises the following main chemical components: 0.03 to 0.07 weight percent of C, less than or equal to 0.35 weight percent of Si, 0.40 to 2.0 weight percent of Mn, less than or equal to 0.020 weight percent of P, less than or equal to 0.010 weight percent of S, 0.25 to 0.80 weight percent of Cr, 0.06 to 0.25 weight percent of Ti and the balance of Fe and inevitable residual elements. In the annealing process, the steel is annealed in a hood-type annealing furnace in the temperature range of 500 DEG C to an A1 transition point. The manufactured high-strength cold-rolled steel sheet with the yield strength level of 700MPa has the advantages of low alloy element cost, single component, the yield strength of higher than 700MPa, the elongation rate of over 5 percent, high machinability and the like.

Description

technical field [0001] The invention relates to a high-strength cold-rolled steel plate with a yield strength of 700MPa and a preparation method thereof. Background technique [0002] The lightweight of automobiles and other vehicles is to reduce the curb weight of automobiles as much as possible under the premise of ensuring the strength and safety performance of automobiles, so as to improve the dynamic performance of automobiles, reduce fuel consumption, and reduce exhaust pollution; experiments have proved that automobiles Halve the mass, and nearly halve the fuel consumption. [0003] At present, high-strength low-alloy steels with microalloying elements are mostly used in cold-rolled steel sheets for general automotive structures. Micro-alloyed high-strength low-alloy steel is mostly low-carbon steel, adding micro-alloying elements such as Nb, Ti, V, B, etc. During rolling and annealing, carbon and nitride second-phase particles are precipitated. These nano-scale fin...

AI Technical Summary

Problems solved by technology

[0011] 1. The investment of continuous annealing furnace is large, the annealing process is complex, especially rapid cooling and other processes are required, the automation of the production line and the requirements for operators are high, and the process operation is difficult

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